This disclosure relates to an actively suspended seat with bass loudspeakers in the seat.
Actively suspended seats can be used in motor vehicles. These seats can decrease or remove vibrations that are transmitted through the seat structure to the driver. Active seat suspension systems are known; examples are disclosed in U.S. Pat. Nos. 8,095,268 and 8,725,351, the disclosures of which are incorporated herein by reference.
Motor vehicle audio systems typically operate in a frequency range of from about 20 Hz to about 20,000 Hz. Such audio systems often include bass loudspeakers. The bass loudspeakers can be used to provide low-end sound. They can also be used as part of an active noise cancellation system, such as an engine harmonic noise cancellation (EHC) system which uses loudspeakers (which are typically but not necessarily the bass loudspeakers that are used by the audio system) to decrease or cancel sound pressure levels in the cabin caused by engine harmonic vibrations. EHC systems are known; examples are disclosed in U.S. Pat. Nos. 8,194,873 and 8,280,073, the disclosures of which are incorporated herein by reference. EHC systems need to radiate sound at the same frequency as the sound to be cancelled, which is commonly in the range of from about 20 Hz to about 200 Hz. For example, for some 6-cylinder motor vehicles that idle at around 600 RPM the third harmonic frequency, which can dominate engine-derived motor vehicle cabin noise and so should be cancelled by an EHC system, is about 30 Hz.